CHEMOSTAT FLOW CELL SYSTEM - AN IN-VITRO MODEL FOR THE EVALUATION OF ANTIPLAQUE AGENTS

We developed an experimental in vitro model of dental plaque to assess the potential efficacy of antiplaque agents. The model used a chemost at, which provided a continuous source of 5 species of oral bacteria g rown in an artificial ''saliva-like'' medium. This mixture was pumped through six flow cells, each containing two types of surfaces on which plaque formed and was subsequently measured. Formation of bacterial p laque on hydroxyapatite surfaces was assessed by measurement of the DN A and protein content of the plaque film. The amount of bacterial plaq ue formed on germanium surfaces was measured by attenuated total refle ctance (ATR/FT-IR) spectroscopy. Plaque viability was also assessed by a fluorescent staining technique. The quantity of plaque formed on bo th types of surfaces gradually increased with the duration of flow (fr om 24 to 72 h) through the cells during a 72-hour experimental period. The flow cells were then pulsed with experimental treatment solutions for 30 s, twice daily. Parallel to results of human clinical studies, the model was capable of discriminating among water, a placebo mouthr inse, and an active antimicrobial mouthrinse formulation containing 0. 03% triclosan. It therefore offers a valuable alternative to animal mo del testing and allows for more rapid evaluations under well-controlle d experimental conditions.